His research focuses on improving the representation of hydrological processes in the Community Terrestrial Systems Model (CTSM). He has developed numerous CTSM parameterizations such as moisture flow in frozen soils, snow covered area fraction, excess soil ice, dry surface layer (soil evaporation), variable soil thickness, and biomass (vegetation) heat storage.  He uses satellite remote sensing (e.g., GRACE, MODIS) and in-situ observations (e.g., from FLUXNET, SCAN) to assess model performance and gain insight into model structural deficiencies. He developed the Hillslope Hydrology scheme in CTSM and the methodologies to create the geomorphic datasets necessary to run the model.